Within the last 10 years, adipose tissues have attracted attention as a resource of multipotent stem cells (See Zuk P A, et al. Mol Biol Cell. 2002; 13: 4279-4295). Adipose tissue consists of mature adipocytes and adipose stromal cells, and the latter can be differentiated into a variety of cell lineages (Zuk P A, et al. Tissue Eng. 2001; 7: 211-228; Hicok K C, et al. Tissue Eng. 2004; 10: 371-380; Erickson G R, et al. Biochem Biophys Res Commun. 2002; 290: 763-769; Cousin B, et al. Biochem Biophys Res Commun. 2003; 301: 1016-1022; Safford K M, et al. Biochem Biophys Res Commun. 2002; 294: 371-379; Miranville A, et al. Circulation. 2004; 110: 349-355; Planat-Benard V, et al. Circ Res. 2004; 94: 223-229; and Planat-Benard V, et al. Circulation. 2004; 109: 656-663) The adipose stromal cells are adhesive and can proliferate in culture. Therefore, a large amount of adipose stromal cells can be readily obtained from a small piece of adipose tissue by means of culture.
Presently in order to produce stromal vascular fraction from adipose tissue an enzyme such as collagenase is typically used. The collagenase dissolves the bonds in the collagen that hold together the tissue. (See e.g., Zuk P A, et al. Mol Biol Cell. 2002; 13: 4279-4295; Zuk P A, et al. Tissue Eng. 2001; 7: 211-228; et al. and the above-cited references).
Collagenases are endopeptidases that digest native collagen in the triple helix region. Collagens are the major fibrous component of animal extracellular connective tissue. Collagenases are present in different organisms including vertebrates and bacteria. Bacterial collagenases have a broad substrate specificity than vertebrate collagenases (See Blumenkrantz et al., J Biol Chem. 1984 Jan. 25; 259(2):854-9; Birkedal-Hansen Methods Enzymol. 1987; 144:140-71. 1987). In addition unlike bacterial derived collagenases split collagen into its native triple helix conformation (See Wooley et al. Eur J Biochem 50(2):437-444, 1975; Gross et al., Animal Collagenases: Specificity of Action, and Structures of the Substrate Cleavage Site, Biochem. Biophys. Res. Commun. 61, 605, 1974). Bacterial collagenases are distinct in that they are capable of breaking down both water-insoluble native collagens and water-soluble denatured collagens. Bacterial collagenases is capable of breaking down almost all types of collagen and can effect multiple cleavages within the triple helical regions (see Mookhtiar and Van Wart Clostridium histolyticum Collagenases: A New Look at some Old Enzymes, Matrix Suppl. 1, 116, 1992).
A recent patent application 20070148766, published Jun. 28, 2007, by Yoshimura; Kotaro; (Shibuya-ku, JP); Matsumoto; Daisuke and assigned to Biomaster Inc., teaches the isolation of stem cells from liposuction-derived aspirates.